1. Technical Field
The invention relates to a circuit board, particularly to a circuit board having a resin composition.
2. Related Art
As developed with wireless transmission products and technologies of transmitting high frequency, epoxy resin and novolak resin cannot satisfied for the advance application, especially high frequency printed circuit board (PCB). Fluorine-containing resin can be used as PCB with low dielectric loss. However, fluorine-containing resin is expensive and not easy to work, and thus limited to the use of military and astrodynamics. In addition, polyphenylene ether (PPE) resin has excellent mechanical property and dielectric property such as Dk and Df. Therefore, the PPE resins are preferable to be used a material for high frequency PCB.
However, because the PPE resin is a thermal plastic resin, as applied in a copper-clad laminate, it may has disadvantages as follows: it is not easy to work due to a high melting viscosity of PPE resin, interlayer film is easy released in a solvent clean step during a process for manufacturing PCB due to a poor solvent resistance of PPE resin, and it is not easy to operate above a temperature of 250° C. in soldering process due to melting point close to Tg. Therefore, PPE resin has to be modified by curing so as to meet the requirement of using in PCB.
Curing modification of PPE resin generally has two manners: PPE resin may become curable resin by introducing crosslinking active functional groups to molecular structure of PPE resin. Alternatively, PPE resin may become co-mixing curable composite material by introducing other curable resins to molecular structure of PPE resin with co-mixing modification or interpenetrating network technology. However, PPE resin is likely incompatible with the active functional groups or curable resins, because the polar difference exists in their chemical structures. Alternatively, PPE resin may lose the excellent properties, after it conducts curing modification with the active functional groups or curable resins.
Therefore, there is a need to develop a circuit board having a material that has excellent dielectric properties and other properties such as high Tg, low coefficient of thermal expansion and low water absorption of PCB requirement. Also, the material can be applied in the manufacture of high frequency PCB.